Title :
p-type Ge-channel MODFETs with high transconductance grown on Si substrates
Author :
König, U. ; Schäffler, F.
Author_Institution :
Daimler-Benz AG, Ulm, Germany
fDate :
4/1/1993 12:00:00 AM
Abstract :
Modulation-doped FET (MODFET) structures with hole channels consisting of pure Ge were grown by molecular beam epitaxy (MBE) on Si substrates. To overcome the relatively large lattice mismatch, between Si and Ge, a relaxed Si/sub 1-x/Ge/sub x /buffer layer with linearly graded Ge concentration and a final x value of around 70% was grown first. Hall mobilities of up to 1300 cm/sup 2//V-s at room temperature and 14000 cm/sup 2//V-s at 77 K were measured. Devices with and without gate recess were fabricated, which result in enhancement- and depletion-type FETs. Maximum extrinsic transconductances of 125 and 290 mS/mm at room temperature and 77 K, respectively, were found for gate lengths L/sub G/ around 1.2 mu m.<>
Keywords :
Ge-Si alloys; Hall effect; carrier density; elemental semiconductors; germanium; high electron mobility transistors; molecular beam epitaxial growth; semiconductor growth; silicon; 1.2 micron; 125 mS/mm; 290 mS/mm; 300 K; 77 K; Ge-Si/sub 1-x/Ge/sub x/-Si; Hall mobilities; I-V characteristics; MODFET; Si substrates; carrier density; depletion-type FETs; enhancement type FET; gate lengths; gate recess; high transconductance; hole channels; lattice mismatch; linearly graded Ge concentration; molecular beam epitaxy; relaxed buffer layer; Buffer layers; Epitaxial layers; FETs; HEMTs; Lattices; MODFETs; Molecular beam epitaxial growth; Substrates; Temperature; Transconductance;
Journal_Title :
Electron Device Letters, IEEE
